Re: window groups

[martin rudalics]

> Could you contrast your proposal with Joakim's `group' window parameter?

AFAIK Joakim leaves the responsibility to set the group parameter to the
application (ECB).  I make Emacs responsible for keeping track of
groups.  To me this means two things:

(1) Groups should conform to internal windows.  Klaus Berndl told me that
    this is the case for ECB's edit area.

(2) `split-window' should be the single interface for creating groups.

> An obvious difference is that his proposal allows groups that do not
> form a rectangle (e.g. ECB could use a group for all the windows around
> the editing area).

Even for rectangles the case is not entirely clear.  In the following
four windows frame

 -----
|  |  |
|--+--|
|  |  |
 -----

we know well that the internal windows differ according to how the first
split was executed.  If the first `split-window' did not have GROUP set
to t and the subsequent ones did there are either two vertically aligned
groups or two horizontally aligned one.

The situation becomes much more complicated when groups may comprise
arbitrary windows of a frame - just think of cloning such a group.  More
problems will arise as soon as two different applications will attempt
to manage their private groups simultaneously in the same Emacs session.